Problem
I use ATI Radeon 6950 GPU, which has audio capability, act as sound device in Windows 7 for its HDMI/Display Port. The sound device is named ATI High Definition Audio device.

However, due to strange implementation of Windows or the driver I don't know whose fault this is, the HDMI audio does not work if there is no accompanying video signal. Currently I attach the HDMI to my AV receiver and video feed is not utilised. (I use DisplayPort for my main display and another auxilliary DVI display). To allow HDMI audio, I have to duplicate my auxilliary desktop as a cloned desktop to my AV receiver (Appears to be a 3rd monitor) so that a video feed signal exists such that the sound works.

This is where problems start. Whenever I turn off my AV receiver or my main monitor, DP/HDMI resyncs. This is when DP/HDMI detects change in connection, performs handshaking protocols and Windows reconfigures the monitor setup to a pre-stored profile. For example, only DP is alive but not HDMI when AV receiver is turned off, the display settings changes accordingly, screen flickers and settles. This is the root of the problem. Upon this, when the resync commences, the connections of all DP/HDMI links reset momentarily and when this happens, the ATI High Definition Audio driver also resets due to loss of link. The speaker icon changes to one with a cross, signifying sound card is unavailable.

Not only does it breaks every application that has active audio resources, due to a bug with the driver or Windows (don't know which), the profiles were not correctly stored and hence restored. If I turn my AV receiver on (from off state) to the profile state where all connections are alive, the profile where monitor is duplicated is not loaded properly and hence the video feed to the AV receiver is not automatically re-established. This mean the sound remains unavailable until I manually re-clone the desktop of my auxilliary monitor to my AV receiver. Similarly, if my desktop is turned off, the resync kicks in and the cloning of the desktop auto breaks.

This means I cannot listen to music with my main display off (even though it's not the one being cloned), or play computer games and go afk since turning off my main monitor breaks the sound and the game (link breakage for the former and resolution reset for latter). God these new interfaces are driving me nuts, can we go to simple plug and play no brainer DVI with audio support?

Question:
Does EDID fix this and if so, how do I go about doing it? Please elaborate step by step, very much appreciated.

P.S. I use a DP to DVI dongle with my main display (a Dell U2711). Before I got this active converter, the scenario was even worse as the U2711, which supports DP audio, tells system it can, and competes with my AV receiver on HDMI. I used to get no audio unless I turn my AV receiver on before U2711. Sign, those who designed the interfaces/drivers deserved to be slamed

AFAIK ATI cards (don't know if it still applies to 7xxx series) do not support multiple audio streams, i.e. only one audio-capable display device gets audio. Needless to say this is a mess if you need to route audio.

The only solution that I can figure out in your case is a Gefen HDMI Detective to be put between the AVR and the TV, which would keep the AVR HDMI connection permanently active. And of course, the AVR should be the primary device so that it gets audio (or in cloned mode).

Thanks, I already spent money to buy a DP-DVI active converter so that the capability of DP audio is masked, so there is no conflicts. However the dongle sometimes is unstable and require unplugging.

Sadly while Gefen will probably solve the problem, it costs about £120 in the UK, which is too expensive in my opinion of something to fix a flaw in the design of the HDMI interface and doesn't add much value :/

There is no TV connected to my AV receiver by the way. The receiver has a HDMI output looping back to my main display (contrived I know) to trick the EDID.

I did recall it not working without HDMI out connection loop back, but that doesn't matter too much as it's just another cable running to my main monitor.

While I am not sure what you mean by primary display device, the sound works as long as video signal is enabled. I cloned my seconady DVI display to my AV receiver dummy connection for the sound to work --- I did not clone my 'primary' display. U2711 does not take 2560x1440 resolution on the HDMI port and it goes haywire. AV receiver appears as the 3rd monitor in Windows display -> screen resolutions so it is not primary either.

Actually come to think of it what I want is a DP keep alive, not a HDMI keep alive device. If I am turning my AV receiver off manually I don't really mind the reset of audio. It is the situation when I want to turn off my main display to save power, which I can't at the moment.

Ok, so let's try the EDID override route. Capture the Dell and AVR real-time EDIDs. Then edit the Dell .inf file and add (or replace) the

HKR,EDID_OVERRIDE,"1", ...

line with the one from the AVR .inf. (It must follow a HKR,EDID_OVERRIDE,"0", ... line).

Save and apply the .inf file to the GenericPnP monitor associated to the AVR-Dell chain (see instructions in my sig.) and reboot.

Hopefully the AMD driver will be fooled into detecting the AVR-Dell as an HDTV (and not a monitor). Otherwise I see no alternative to the Gefen.

I didn't do any hack but Windows already detects the AVR as HDTV, not a monitor. Not sure what difference it makes. Correct me if I am wrong, the culprit of my problems are the loss of EDID signal when monitor/AVR goes offline (switched off), which then triggers low level OS/driver resyncs, which then breaks the sound system.

Since there are no DisplayPort EDID hardware on the market, I went ahead and bought a cheapo (kind of) 2nd hand DVI EDID (Gefen DVI detective N) hardware (since I have a DP - DVI converter). I will see how that goes.
It won't solve all my problems, but I will be able to decouple the power status of my main monitor from affecting the system. I will need to buy the HDMI detective too for the AVR to solve all my problems, and that's a bit out of my budget at the moment.

I didn't do any hack but Windows already detects the AVR as HDTV, not a monitor. Not sure what difference it makes. Correct me if I am wrong, the culprit of my problems are the loss of EDID signal when monitor/AVR goes offline (switched off), which then triggers low level OS/driver resyncs, which then breaks the sound system.

Yes, of course. But if HDMI audio is still disabled after powering on it means that the AVR link is being detected with a default monitor (with no audio) profile. If you override it with a monitor driver that has the audio descriptor of the AVR, HDMI audio should be enabled after the AVR is switched on as Windows will use the overridden EDID instead of the default one with no audio.

Oh right I see actually it comes on all the time if I turn back on my AVR after it is off, provided I have not turned off my main monitor any time in between. If I have turn off my monitor off and on (then it should be back to the previous state), strangly resetting my AVR then does not re-enable the sound anymore. This is the case until I manutally clone the display again and the cycle of behavior repeats. I can't explain this rather than a glitch with the drivers/Windows.